Platinum group metals have excellent electrical, chemical and physical properties, occupy an important position for not only in typical jewel industries, but also as electronic industry materials, and its demand is increasing. In addition, its chemical property at high temperatures is stable, so the platinum group metals are widely used for aerospace materials and petrochemical and automobile catalysts, and are widely used industrially and commercially in electrical and medical industries requiring corrosion resistance.
Further, as the demand increases, the amount of industrial waste such as wasted electronic device scraps, petrochemical spent catalysts, automobile spent catalysts, etc. being generated is rapidly increasing, and highly priced precious metals such as gold, silver, palladium, rhodium, etc. and various valuable metals such as copper are included in the waste, so the waste may be a secondary resource. In this case, when the platinum group metals are recovered in a high recovery rate by using the spent catalysts, which are not processed and wasted, the material may realize high value addition and may be used as core technology for technological development, and may be used as a material for high purity rare metals and platinum group elements as well as catalysts.
In the case of the platinum group metals used for this usage, the mineral resource is scarce and the endowed area is concentrated, so the price is high and the entire quantity is imported, thus a method of recovering platinum group metals from spent catalysts, which include the platinum group metals, is demanded.
As a related art, a method of recovering platinum group metals by leaching rhodium, platinum and palladium, which are platinum group metals included in alumina carriers, by using aqua regia, has been proposed, however, platinum and palladium may be leached by aqua regia but rhodium is not leached at all, and the cost of processing the discharged waste from this process is high.
As a related document, a method of leaching platinum group metals from automobile spent catalysts is disclosed in Korean Unexamined Patent Publication No. 10-2010-0124030 (published on Nov. 26, 2010).